Apparently I never learn the lesson.

I'm doing camp again this summer. The pay for three weeks of full-on kids and activities in the stinking heat of Dongguan summers used to pay for my flight home and back again. Since air fares have increased so much, it doesn't go quite as far as it used to, but still covers a hefty share of the travel budget.
Every year I say 'never again' and every year I find myself saying 'yes' when asked. Why? It's fun.
Yes, I work hard. But I also get to play hard, with the kids and with other FTs. The down times hanging out in the teachers' lounge are some of my favorite times with expats in China. I like swapping ideas with other teachers and trying new things. Camp gives me that opportunity. It's different enough from my real job that it almost (don't laugh) seems like a vacation.
Yes, the kids are little monsters. They are also little darlings. They grow on me. And then - poof - camp is over and I never get to see them again.
Despite what I say to myself at the end of camp every year, apparently I like it enough to keep coming back. It's not for everyone, that's for sure.
About the visa issue - Three years ago my niece and her boyfriend came from Canada on tourist visas and did a 3-week camp in Dongguan. The camp was at The Party conference center. I'm not sure what the camp leaders did about registering them with the authorities. They were paid in cash. It's do-able. Probably not legal, though.